JP3242521B2 - Manufacturing method of titanium alloy ring - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a titanium alloy ring.

[0002]

2. Description of the Related Art A titanium alloy ring is generally manufactured in the following manner. ： Titanium alloy ingot is heated to β region and forged into a forged mass, and the ingot is heated to α + β region and forged into a billet of desired size. I do. : The above billet is machined into a hollow hollow billet. : The hollow billet is heated to the α + β region and ring-forged, or ring-forged and then rolled to produce a titanium alloy ring.

[0003] In the above-mentioned ring forging, the equipment shown in FIG. 4 is used. The hollow billet 1 heated to the α + β region is passed through the mandrel 4, and both ends of the mandrel 4 are received by the receiving stand 6, and are not shown in this state. The anvil 5 attached to the press is moved up and down, whereby the material is reduced between the mandrel 4 and the anvil 5 to reduce the thickness and increase the diameter.

[0004]

By the way, it is known that a titanium alloy has a crystal structure of dense hexagonal crystal (hcp), and is liable to crack during processing at a β transformation temperature or lower. Therefore, in order to prevent cracking during this processing, conventionally, as described above, after giving a fixed amount of forging in the β region (body-centered hexagonal crystal (bcc)), the forging in the α + β region is fixed. A process is adopted in which a microstructure is refined by performing a solution treatment to give a constant amount, and a constant amount of forging is performed in an α + β region to obtain an equiaxed structure.

[0005] However, the above process can be employed without any problem when a solid body such as a titanium alloy billet is manufactured. However, as described above, after the β solution treatment, the hollow billet is machined into a hollow billet, and the ring is formed in the α + β region. When manufacturing a titanium alloy ring by forging, cracks may occur at the billet end during ring forging, particularly when the ring is further rolled with a ring rolling machine after the ring forging, the cracks become remarkable, In extreme cases, cracks may be too large to produce a ring product. In addition, the yield is reduced.

The present invention has been made in view of the above problems, and an object of the present invention is to suppress cracking at the end portion during ring processing when expanding the diameter from a titanium alloy hollow billet to a titanium alloy ring. The present invention provides a method of manufacturing a titanium alloy ring that can be performed.

[0007]

In order to achieve the above object, one of the methods for manufacturing a titanium alloy ring according to the present invention is to provide a ring for preferentially forging an end of a titanium alloy hollow billet in an α + β region. After forging, the ring is forged or rolled to produce a titanium alloy ring.

In the above method for manufacturing a titanium alloy ring, it is desirable that the rolling reduction when preferentially forging the end of the titanium alloy hollow billet in the α + β region is 5% or more.

[0009]

The structure and operation of the present invention will be described below in detail. As described above, a process for forging a titanium alloy forging in the α + β region is usually performed after forging in the β region.
This is a needle-like structure after β-forging and is easily broken. However, if sufficient α + β forging is performed thereafter, the structure changes from a needle-like structure to an equiaxed structure, and an equiaxed structure hard to crack is obtained. However, in the ring forging of the conventional titanium alloy in the α + β region, the ring end is apt to be broken during ring forging. This is because the titanium alloy hollow billet is pressed down between the mandrel and the anvil to reduce the wall thickness and enlarge the diameter. Can be Therefore, in the present invention, in order to improve the structure of the end portion from a fragile needle-like structure to an equiaxed structure that is difficult to crack before cooling, α
The end is forged preferentially in the + β region.

As a method of forging the end portion preferentially, as shown in FIG. 1, an anvil 2 of about half the length of a titanium alloy hollow billet 1 is used. On the other hand, the other end is then lowered, and then the central portion is forged by pressing. Alternatively, as shown in FIG. 2, the anvil 3 is longer than the titanium alloy hollow billet 1 and the central portion is depressed. For example, there is a method in which both ends of the hollow billet 1 are preferentially reduced and forged. In the latter case, the outer periphery of the ring material is forged flat with an anvil having a flat bottom surface. In the figure, reference numeral 4 denotes a mandrel.

FIG. 3 shows a state in which a titanium alloy hollow billet is lowered between a mandrel and an anvil in ring forging.
This is a plot obtained by three-dimensionally analyzing the apparent strain [the amount of reduction (%)] in the rolling direction and the maximum true strain at the end by the finite element method. In the figure, the conventional method is a case where the entire length of the hollow billet is simultaneously reduced by using an anvil 5 longer than the length of the hollow billet 1. The method A of the present invention
Fig. 4 shows a case where the pressure is reduced by using the anvil 2 shown in Fig. 1. Further, the method B of the present invention is a case where the pressure is reduced by using the anvil 3 shown in FIG.

As is apparent from FIG. 3, even when the same amount of reduction is applied to the titanium alloy hollow billet, the maximum true strain applied to the end of the titanium alloy hollow billet is determined by the method of the present invention A and the method of the present invention. Method B is large and the conventional method is almost half of the method of the present invention. Therefore, in general, to improve the structure of a titanium alloy from an acicular structure to an equiaxed structure, a maximum true strain of 0.
It is said that it is necessary to provide 2 or more. However, in order to provide this, if the invention method A and the invention method B are used, the reduction amount can be 5% or more. In the case where the same amount of reduction of 10% as that in the case of imparting the same is applied, sufficient structural improvement can be achieved. For this reason, the amount of reduction when preferentially forging the end of a titanium alloy hollow billet is 5%.
%, But the upper limit is preferably about 20%. If a larger amount of reduction is given, there is a concern that the quality (cylindricity, roundness, etc.) of the ring material after forging may be impaired. In the method A of the present invention and the method B of the present invention, the reason that the method B of the present invention can provide a larger maximum true strain than the method A of the present invention even with the same reduction amount is that both ends are restricted in the method B of the present invention. Therefore, the movement of the material in the axial direction at the end is mainly in the outward direction only. (In the method A of the present invention, the movement of the material in the axial direction at the end is limited by the center of the anvil 3 because the material is reduced one by one. Therefore, it is considered that a large strain can be given to the end portion.

[0013]

Embodiments of the present invention will be described below. (Example 1) Titanium alloy having a diameter of 420 mm (Ti-6Al-4V)
Using an ingot, a titanium alloy ring was manufactured through the following processing steps.

The above titanium alloy ingot was heated to 1200 ° C., which is a β region, and slab-forged to a diameter of 340 mm. : The above forged mass was heated to 950 ° C. in the α + β region and forged to a diameter of 300 mm. : After forging the above forged material (heating at 1050 ° C x 30 minutes followed by water quenching), the outer diameter is 300mm x inner diameter 125mm by machining.
× Processed into a 400 mm long hollow billet. : The above hollow billet was heated to 950 ° C. in the α + β range, and the ring forging was performed using a ring forging device having a mandrel having a diameter of 120 mm and an anvil having a width of 250 mm as shown in FIG. The ring was forged in the same manner at the center, and this was repeated to forge a ring with an outer diameter of 500 mm and an inner diameter of 430 mm. : After the ring forging material was pressed with a press to flatten both end surfaces, the ring forged material was heated to 950 ° C., which is an α + β region, and was ring-rolled by a ring rolling machine to an outer diameter of 700 mm and an inner diameter of 650 mm.

Cracks were not observed at both ends of the titanium alloy ring product obtained by the above-mentioned processing step, and no defect was found by ultrasonic flaw detection, and a good product was obtained. In addition, ring forging and ring rolling were performed smoothly, and the yield was greatly improved.

Example 2 A titanium alloy having a diameter of 420 mm (Ti
−6Al-4V) Using an ingot, a titanium alloy ring was manufactured through the following processing steps.

The titanium alloy ingot was heated to 1100 ° C., which is a β region, and then continuously forged to a diameter of 300 mm. : The above forged material is machined to an outside diameter of 300mm x inside diameter of 1
It was processed into a hollow billet of 25 mm x 400 mm in length. : Α + β without hollow treatment of the above hollow billet
After heating to 950 ° C, which is a temperature range, using a ring forging device shown in Fig. 2 equipped with a mandrel with a diameter of 120mm and an anvil with a 250mm indent width, a ring forging is performed at both ends with a rolling reduction of 10%. The ring was forged with an anvil, and this ring forging was repeated to forge the ring to an outer diameter of 500 mm and an inner diameter of 430 mm. : After the ring forging material was pressed with a press to flatten both end surfaces, the ring forged material was heated to 950 ° C., which is an α + β region, and was ring-rolled by a ring rolling machine to an outer diameter of 700 mm and an inner diameter of 650 mm.

No cracks were observed at both ends of the titanium alloy ring product obtained in the above-mentioned processing step as in the case of the above-mentioned Example 1, and no defect was found even by ultrasonic flaw detection, and a good product was obtained. . In addition, ring forging and ring rolling were performed smoothly, and the yield was greatly improved.

[0019]

As described above, according to the method for manufacturing a titanium alloy ring according to the present invention, when the diameter is increased from the titanium alloy hollow billet to the titanium alloy ring, the end portion during ring forging or ring rolling is used. Cracking can be suppressed,
As a result, a high quality titanium alloy ring can be manufactured with good yield.

[Brief description of the drawings]

FIG. 1 is a schematic view of a ring forging device used in a method for manufacturing a titanium alloy ring of the present invention.

FIG. 2 is a schematic view of a ring forging apparatus of another embodiment used in the method for manufacturing a titanium alloy ring of the present invention.

FIG. 3 is a graph showing the relationship between apparent strain [reduction amount (%)] in the rolling direction and the maximum true strain at the end when a titanium alloy hollow billet is lowered between a mandrel and an anvil in ring forging. .

FIG. 4 is a schematic view of a ring forging device used in a conventional titanium alloy ring manufacturing method.

[Explanation of symbols]

 1: Titanium alloy hollow billet 2, 3: Anvil 4: Mandrel

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hirofumi Morikawa 2-3-1, Shinhama, Araimachi, Takasago City, Hyogo Prefecture Inside Kobe Steel, Ltd. Takasago Works (72) Inventor Toshiyuki Ochi 2-3, Araimachi Shinama, Takasago City, Hyogo Prefecture No. 1 Kobe Steel, Ltd. Takasago Works (72) Inventor Ryo Onishi 2-3-1, Shinama, Araimachi, Takasago City, Hyogo Prefecture Kobe Steel Co., Ltd. Takasago Works (72) Inventor Hiroyuki Morito Takasago, Hyogo Prefecture 2-3-1, Shinhama, Araimachi, Kochi, Japan Inside Kobe Steel, Ltd. Takasago Works (56) References JP-A-53-1617 (JP, A) JP-A-56-131036 (JP, A) JP-A-51-109261 JP-A-61-110756 (JP, A) JP-A-63-130754 (JP, A) JP-A-64-28347 (JP, A) JP-A-1-228661 (JP, A) Kaiping -169445 (JP, A) JP flat 5-25597 (JP, A) (58 ) investigated the field (Int.Cl. ^7, DB name) B21J 1/00 - 13/14 B21J 17/00 - 19/04 B21K 1/00-31/00

Claims (2)

(57) [Claims] 1. A titanium alloy ring manufactured by performing ring forging for preferentially forging an end of a titanium alloy hollow billet in an α + β region, and further performing ring forging or ring rolling to produce a titanium alloy ring. Manufacturing method. 2. The method for producing a titanium alloy ring according to claim 1, wherein the amount of reduction when preferentially forging the end of the titanium alloy hollow billet in the α + β region is 5% or more.